Zamboanga Peninsula is an administrative region in the Philippines, designated as Region IX. It consists of three provinces including four cities and the highly urbanized Zamboanga City. The region was previously known as Western Mindanao before the signing of Executive Order No. 36 of 2001. The city of Zamboanga was designated as the regional center until Pagadian was designated as its new regional center, although Zamboanga City remains the region's cultural, commercial, economic, and educational center.

Pagadian, officially the City of Pagadian, is a 1st class component city and the capital of the province of Zamboanga del Sur, Philippines. It is the regional center of Zamboanga Peninsula and the second-largest city in the region and in the province, after the independent city of Zamboanga. According to the 2020 census, it has a population of 210,452 people. The city will be converted to a highly urbanized city by the virtue of Proclamation No. 1247, signed by President Rodrigo Duterte dated November 8, 2021.